Refrigerating machine oils in which a mineral oil is used as the base oil are widely used in refrigerating and air conditioning machines that make use of R22 and other such HCFC (hydrochlorofluorocarbon) refrigerants (see the patent documents 1 and 2)    [Patent document 1] Japanese Patent Application Laid-Open No. S55-84879    [Patent document 2] Japanese Patent Application Laid-Open No. S56-157487